• Currently

    Reported at Medford, Rogue Valley International Airport, OR
    7:53 AM PST SUN SEP 24 2017
  • 48°F9°C
  • Clear
    Clear
  • Feels Like:48°F9°CDew Point:43°F6°CHumidity:82% Winds: Calm Calm
    Pressure:30.15 in1021 hPaVisibility:10.00 miles16090.00 meters
  • Area Forecast Discussion

906 AM PDT Sun Sep 24 2017

.DISCUSSION...Satellite imagery shows areas of low clouds in Coos
County and northwestern Douglas County. Low clouds also extends
into the coastal waters about 10 nm from shore. We expect the low
clouds to burn off by noon but short term model brings the low
clouds back to the Coos Bay area again this afternoon and tonight.
Grids were updated to account for the sky cover.

We are still on track for a warming and drying trend. Inland high
temperatures today and Monday will be close to season norms, then
ramp up to about 5 degrees above normal Tuesday. Temperatures
could be about 10 degrees above normal from Wednesday through the
end of the week with upper 80s possible for the Rogue Valley.

The atmosphere will also be quite dry in the second half of the
week and this could present some fire weather concern especially
lower humidity at night at the upper slopes and ridges. /FB

&&

.AVIATION...24/12Z TAF CYCLE...Patchy IFR to LIFR fog and low
ceilings are expected to continue along and near the coast north of
Cape Blanco, to include in the Coquille Basin, through at least
early morning before dissipating. These conditions will likely
return this evening and remain overnight. Isolated and brief
MVFR/IFR visibilities in radiation fog are also possible in the
Umpqua Basin around sunrise this morning. Otherwise, VFR will
prevail. SK/BTL

&&

.MARINE...Updated 800 AM PDT Sunday, 24 September 2017...A thermal
trough will maintain gusty north winds and steep seas south of Cape
Blanco through early next week. Winds and seas will peak each
afternoon and evening through Tuesday, and small craft advisory
conditions will spread north today to cover a broader area south of
Cape Blanco. North winds may increase even further late Tuesday
afternoon into Tuesday evening and bring a mix of steep to very
steep seas south of Cape Blanco with steep seas and small craft
advisory winds possible north of Cape Blanco. There is also
potential for gale force gusts south of Cape Blanco during this time
period as well. North winds will diminish Wednesday into Wednesday
night. SK/BTL

&&

.FIRE WEATHER...Updated 200 AM PDT Sunday, 24 September 2017....
A warming and drying trend is expected through most of the week. Of
note is the recent GFS model trend showing a solidly dry air mass
Wednesday through Friday, to include potential for poor to moderate
humidity recoveries each night during that period. Temperatures are
expected to peak, and humidity values are expected to be at their
lowest, around Thursday as the thermal trough moves inland. Breezy
and dry is a fair characterization of the fire weather environment
towards the coast south of Cape Blanco and in Western Siskiyou
County. Additionally, those favored north to south oriented valleys
like the Umpqua and Illinois, will see breezy conditions during the
afternoons, along with the East Side.

At no time during the next week do we expect critical fire weather
conditions. There will be periods of breezy and dry conditions, but
winds and humidity aren`t expected to align enough to warrant any
Fire Weather Watches or Red Flag Warnings.

Looking further out and considering the past several days of model
data, the mostly dry and warmer than normal conditions should
generally persist through week 2. However, there are very recent
trends in the GFS model that suggest some wetting rains are possible
next week. -SK

&&

.PREV DISCUSSION... /Issued 628 AM PDT Sun Sep 24 2017/

Updated aviation discussion.

DISCUSSION...Model agreement remains very good through Thursday.
A broad ridge is currently offshore and will be the main driver of
warmer and drier weather as it moves slowly east through that
time. Unlike a typical summer-time ridge, this ridge will have a
series of disturbances ride over its northern edge into the
Pacific Northwest. These will continue to bring variable amounts
of mainly mid and high level clouds. An exception is the band of
low clouds presently along the coast north of Cape Blanco into the
Coquille Valley. These clouds are expected to dissipate late this
morning with another shallow marine stratus layer likely to
develop again this evening.

Among the more notable of the disturbances is a front that will
bring rain into Washington on Monday with a slight chance to
chance of light rain into the Oregon coastal waters and northwest
Oregon. The most likely scenario is that it delivers some
sprinkles or a brief shower to Coos and Douglas Counties on Monday
afternoon and evening.

An along-shore to onshore low level flow will follow at the coast
north of Cape Blanco into the Coquille Valley on Monday night
with a thicker marine stratus into Tuesday morning that may bring
patchy drizzle. An easterly flow is likely along all of the coast
on Tuesday night which would limit or exclude low clouds. Meantime,
low clouds are not expected at the coast south of Cape Blanco from
this morning through Wednesday morning with a persistent dry east to
northeast flow. This will also bring above normal temperatures to
the Brookings area with highs in the 70s to lower 80s. Elsewhere,
the forecast continues with a model blend of high temperatures.
This generally shaves a few degrees off the GFS MOS forecast, but
still represents inland highs around normal today and Monday then
becoming around a half-dozen to a dozen degrees above normal for
Wednesday and Thursday. Wednesday and Thursday will compete for the
title of warmest day of the week as the coastal thermal trough moves
inland then retreats back toward the coast Wednesday night before
moving to the east side on Thursday.

Beyond Thursday, a cold front is still expected to approach on
Friday or Friday night. This front is likely to be stronger than the
Monday system, but not by a lot. The ECMWF is slightly faster and
stronger than the GFS but still has the front weakening as it moves
inland and only indicates a few light showers possible at the coast.
Both models indicate a ridge offshore from California will build on
Saturday with The ECMWF showing a slightly more amplified solution.

Model agreement diminishes quickly and significantly beyond
Saturday. The forecast reflects a model blend but leans toward  the
ECMWF and persistence. The higher amplitude of the ECMWF solution
allows the ridge to persist while the GFS solution shifts to a cool
and wet pattern.

AVIATION...24/12Z TAF CYCLE...Patchy IFR to LIFR fog and low
ceilings are expected to continue along and near the coast north of
Cape Blanco, to include in the Coquille Basin, through at least
early morning before dissipating. These conditions will likely
return this evening and remain overnight. Isolated and brief
MVFR/IFR visibilities in radiation fog are also possible in the
Umpqua Basin around sunrise this morning. Otherwise, VFR will
prevail. SK/BTL

MARINE...Updated 300 AM PDT Sunday, 24 September 2017...A thermal
trough will maintain gusty north winds and steep seas south of Cape
Blanco through early next week. Winds and seas will peak each
afternoon and evening through Tuesday, and small craft advisory
conditions will spread north today to cover a broader area south of
Cape Blanco. North winds may increase even further late Tuesday
afternoon into Tuesday evening and bring a mix of steep to very
steep seas south of Cape Blanco with steep seas and small craft
advisory winds possible north of Cape Blanco. There is also
potential for gale force gusts south of Cape Blanco during this time
period as well. North winds will diminish Wednesday into Wednesday
night. SK/BTL

FIRE WEATHER...Updated 200 AM PDT Sunday, 24 September 2017....
A warming and drying trend is expected through most of the week. Of
note is the recent GFS model trend showing a solidly dry air mass
Wednesday through Friday, to include potential for poor to moderate
humidity recoveries each night during that period. Temperatures are
expected to peak, and humidity values are expected to be at their
lowest, around Thursday as the thermal trough moves inland. Breezy
and dry is a fair characterization of the fire weather environment
towards the coast south of Cape Blanco and in Western Siskiyou
County. Additionally, those favored north to south oriented valleys
like the Umpqua and Illinois, will see breezy conditions during the
afternoons, along with the East Side.

At no time during the next week do we expect critical fire weather
conditions. There will be periods of breezy and dry conditions, but
winds and humidity aren`t expected to align enough to warrant any
Fire Weather Watches or Red Flag Warnings.

Looking further out and considering the past several days of model
data, the mostly dry and warmer than normal conditions should
generally persist through week 2. However, there are very recent
trends in the GFS model that suggest some wetting rains are possible
next week. -SK

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Wednesday for PZZ35
6.
     Small Craft Advisory until 5 AM PDT Wednesday for PZZ376.
     Hazardous Seas Watch from Tuesday afternoon through late Tuesday
     night for PZZ376.

$$

FJB/FJB/NSK